Billions of miles beyond Neptune spins a world so fast it has stretched itself into the shape of a squashed football. This deep dive explores Haumea, the dwarf planet nicknamed Santa when it was spotted around the holidays, the third largest known trans-Neptunian object after Eris and Pluto, and the fastest rotating equilibrium body in the solar system with a 3.9-hour day. The episode explains how astronomers deduced its triaxial ellipsoid shape from light curves, then confirmed it through a 2017 stellar occultation that also revealed a 70-kilometer-wide ring at a radius of about 2,287 kilometers, the first ever found around a trans-Neptunian object.

It digs into the chemistry mystery of a surface that is 66 to 80 percent crystalline water ice at 50 Kelvin, where radiation should have degraded it to amorphous ice within 10 million years, an ...